Bruno

I have a 2 bar map sensor and I would like to map the compu as if I have a 3 bar map sensors. what will happen to the sensor, I wont get more that 10 pounds of boost. The reason for this is because I dont want to buy the 3 bar sensor, and I realise that it is easir to map the compu when using the 3 bar sensor.
any comments anybody?

jetenginedoctor

What do you hope to accomplish here? How much boost will you be making? The difference in price between a 2 bar and 3 bar MAP sensor isn't that much. Why not sell your 2 bar sensor and buy a 3 bar? What I suspect you have in mind WILL NOT WORK. Be a bit more explicit with what you've got planned, and I'll give you a better explaination.

BK

Bruno

well have you ever try to map your fuel with a 2 map sensor? is more dificult to do it in a 2 map sensor than a 3 bar map sensor, Originally I bought the 2 bar map sensor thinking that I was not going togo more than 14 psi.
I have map the haltech with a 3 bar map sensor in another car and it is alot easier, especially when the engine has no boost. with the 2 bar map sensor the readings are a bit more jumpy and are harder to figure out where the mixture is lean or rich. I use a wideband sensor to map the fuel.
Now can you get an idea of what I am talking about here.

jetenginedoctor

Bruno,

The reason that it seems tuning is more jumpy with the 2 bar MAP than the 3 bar is the fact that the number of load points is spread over a greater span with the 3 bar MAP sensor than with the 2 bar MAP sensor.

Look at it this way. With the E6K (for example,) there are 32 load points for each RPM range. If you use a 1 bar MAP sensor, those 32 points are split up between 0 and 100 kpa. Therefore, each 3.125 kpa change in manifold pressure will result in the carrot (pointer) landing on a different load point. Using a 2 bar MAP sensor means that every 6.25 kpa change in manifold pressure results in a change in carrot load point position. Finally, using a 3 bar MAP, each 9.375 kpa change in manifold pressure will result in the carrot moving either up or down one load point.

The point that I'm trying to get across to you, is that the higher 'bar' MAP sensor you use, the greater the change in manifold pressure/engine load will have to occur before you see a resulting change in load bar in the tuning software. Just because the carrot moves around more doesn't mean that it's more difficult to tune. IN FACT, I reccomend that people use a 2 bar MAP sensor rather than a 3 bar in most cases. The reason for this is that the tuning resolution is much better with the 2 bar than the 3 bar sensor, and that the engine runs at peak manifold pressure for such a very small portion of time, that it's really silly to trade tuning resolution for the higher MAP you'll reference during tuning.

In other words. . . if your car makes a maximum of 20 psi of boost, use a 2 bar MAP. If it makes 25 psi, use a 2 bar MAP. If it makes 30 psi, then I'd start to consider using a 3 bar MAP. The ultimate solution is to use a 2 bar MAP sensor for the ECU load reference for fuel and ignition tuning, then use a 3 bar MAP sensor on an extra input for additional datalogging data along with the output of a wideband A/F meter. THEN, you can study the need for enrichment/spark retard at pressures above what the 2 bar MAP sensor will measure, and tune for those pressures by making changes to the two highest load bars on the fuel/timing maps. Its easier to show than to explain, but trust me on this. You're much better off sticking to the 2 bar MAP sensor in most cases.

BK